Sexual dimorphism exists in P. vannamei shrimp (ZZ/ZW determination system) with females having a higher growth rate than males1-2. A mono-sex culture program (ALL-FEMALE SHRIMP) may increase the economic return of shrimp farming by mapping the sex-determination region in this species, which may assist in improving economic relevant traits like reproduction and growth, and study recombination rates and transposable elements (TE). A TE (RTE-3_LVa) has been identified as a potential female sex marker in P. vannamei3.
Garcia et al. (2024) reported a genetic map that yielded 15,256 single nucleotide polymorphisms (SNPs) assigned to 44 linkage groups (LG). LG18 was found to be the largest for both sexes, whereas LG44 was the shortest for males and LG31 for females4. They identified a sex-determining region in LG31 with 21 statistically significant SNPs4, the most important SNP was previously identified as a sex-linked marker5 and was able to identify 99% of the males and 88% of the females4. The oplophorus-luciferin 2-monooxygenase, serine/arginine repetitive matrix protein and spermine oxidase genes were identified as candidates with possible participation in important processes of sexual differentiation in shrimp4. Yu et al (2017) identified a sex-determining loci in LG18 of the reference genome5. Two microsatellites in sex LG of shrimp (LG4, ShrimpMap7) are similar to the sex-linked marker in LG184.
To confirm the ZZ/ZW determination system, efforts are underway to sequence the genome of a wild female P. vannamei from Ecuador using long-read sequencing to assemble 45 chromosomes, even if it will be more challenging to assemble than ZZ males. Considering that there are only five draft genome assemblies available for P. vannamei6, a new chromosome-based genome is needed.
References
1. Moss, DR, Hennig, OL, Moss, SM. 2002. Sexual growth dimorphism in penaeid shrimp. Potential for all female culture. Global Aquaculture Advocate, 2002.
2. Wang, T, Yu Y, Li, S, Li, F. 2024. Molecular mechanisms of sex determination and differentiation in decapod crustaceans for potential aquaculture applications: An overview. Rev Aquac. 2024;1‐21. doi:10.1111/raq.12924. 3. Zuniga et al. 2024, Aquaculture 2025 meeting, New Orleans, March 6-10, 2024.
4. Garcia, B.F., Mastrochirico-Filho, V.A., Gallardo-Hidalgo, J. et al. A high-density linkage map and sex-determination loci in Pacific white shrimp (Litopenaeus vannamei). BMC Genomics 25, 565 (2024). https://doi.org/10.1186/s12864-024-10431-x.
5. Yu Y, Zhang X, Yuan J, Wang Q, Li S, Huang H, et al. 2017. Identification of sex determining loci in Pacific White shrimp Litopeneaus vannamei using linkage and Association Analysis. Mar Biotechnol. 19:277–86. 6. Alcivar-Warren et al. Aquaculture 2025 meeting, New Orleans, March 6-10, 2024.
7. Alcivar-Warren, A, Meehan-Meola D, Park SW, Xu Z, Delaney M, Zuniga G. 2007. SHRIMPMAP: a low-density, microsatellite-based linkage map of the Pacific whiteleg shrimp, Litopenaeus vannamei: identification of sex-linked markers in linkage group 4. J Shellfish Res. 26:1259–77